Apparatus for amplifying or detecting electrical variations.



- G. W. PIERCE.

APPARATUS FOR AMPLIFYING 0R DETECTING ELECTRICAL VARIATIONS. APPLIOATION FILED NOV. 26, 1913.

1,Q87,1 80. Patented Feb. 17, 1914.

2 SHEETS-SHEET 1.

G. W. PIERCE. Y

APPARATUS FOR AMPLIFYING 0R DETECTING ELEGTRIGAL VARIATIONS.

APPLICATION FILED NOV. 26, 1913.

Patented Feb. 17, 1914.

2 SHEETS-SHEET 2.

Mama; M, flr wd V @f we www New

' for amplifying or detectingelectrica UNITED STATES PATENT OFFICE.

. J GEORGE W. IIEMI, OI OAIEEIDGE, MASSACHUSETTS.

APPAD LTUI I'OI manure 0E DETECTING ELECTRICAL VARIATIONS.

museums of Letters latent.

Patented Feb. 17, 1914.

Application ans Icvsmber as, me. burial in. soaass.

To all whom it may concern Be it known that I, Gnoiioii PIERCE, a citizen of the United States, residing at Cambrigfe, in the county of Middlesex and Sta of ssachusetts, have invented certain new and useful Improvements iii'Apparatus'tor Amplifyin or Detecting Electrical Variations; and do hereby declare the f ollowin to be a full, clear, and exact description 0 the invention, such as will enable others .skilled in the art to which it appertainsto make and usethe same.

The present invention relates to apparatus variations. The apparatus comprises a aseous conducting medium upon which t e electrical variations are impressed in such a manner as to modi the current in a local. circuit throught e gas.

-The objectof the invention is to make an improved a paratus of this type wh ch is sensitive, re able and re idlx responsive to the variations to be amp ifi e The apparatus is particularly ap licable to the am lification or detection of t e electric signa variations or impulses 0i wireless telegraphy, wireless telephony, or telephony and telegr'aphy over wires and cables.

The res'e'ut invention is pref erably embodied in an' apparatus comprising a mercury vapor device in wh ch an evacuated s ace or region is ionized and rendered con ucting by means ofa mercur arc. The Electrical variations to be amp itied or detected are impressed by means of a'cont'rolling circuit upon a region in the ionized conducting gas or va or and vary its apparent conductivity. A coal or controlled circuit has a current path through the conducting gas or vapor. The change in the appareut conductivity of the gas causes variations in the current in the controlled circuit. These variations in the controlled circuit may be detected by some translating device in the controlled circuit or connected indirectly therewith.

In the drawings which illustrate the prefci'rcd embodiment of the presentinventicn, Figure 1 is a diagrammatic view oft-he mercury vapor device connected with a tele: phone line; Fig. 2 shows the mercury va or device connected'witli' a tale aph line; lip.

8 is a plan view or the shiel and Fig. a Ian 'view' of the grid-like electrode.

mercury vapor deviceper as will first be described and then the electrical connections and mode of operation will be described and pointed out.

The mercury va r device comprises an evacuated glass buil or tube 1. Supported on a leading-in wire which is scaled through the top of the tube is an electrode 2 which consists of a fiat circular plate or disk of platinum or iron. A short distance below the electrode 2 is another electrode 3 which consists of a piece of platinum or iron wire bent back and forth to form a grid as shown in Fig. 4, and connected with a leading-iii wire sealed through the side of the tube.

The electrode 3 may have the form of a grid,

as illustrated, or may be made of a foraminate plate or of wire fabric or other open work structure. Sealed through the bottom of the tube is a platinum wire 4 which projects some distance into the tube. Above the platinum wire su ported by a leading-in wire sealed throng the side of the tube is an electrode 5 which consists of a flat circular plate or disk of iron with a liole8 throu h it. This hole 8 is situated directly above t is point of the platinum wire 4. The tube contains a body of liquid mercury 6, the level of which is such that the point of the platinum projects sli htly from the surface of the mercury. extension 7 is blown into the sideof the tube near the bottom into which the surplus mercury may be spilled to adjust the mercury level with respect to the latinum wire. The circular perforated plate 5 and the body of mercury 6 form the electrodes or terminals for a mercur are which is maintained by means of a Keep alive circuit 10 which includes the battery 11 and ballast resistance 12 and inductance 13. The platinum wire 4 acts to hes the are from skippin around over the surihce of the mercury an holds it at the point of the platinum-wire. The action of the mercury arc in conjunction with the controlled circuit 30 hereinafter described is believed to causes stream of negative ions or electrons to arrive at the surface of the electrode 2 by flowing chiefly through the hole 8 in the plate 5. The plate intercepts the electrons around the hole 8 and so shields the u per part of the tube from the electrons discharged from the arc with the exception of the stream flowing throu h the hole 8 or a comparatively animpor ant indirect flow around the edge of. the late 5. Since the are is centered below the ole 8,aooncentrated and directed stream of electrons is directed throu h the hole 8 and upon the electrode 2 at t e top of the tube. The plate 5 besides being a positive electrode or anode has, as above pointed out, the function of substantially shielding the upper part of the tube from theelectrons given of! by the arc except for the directed stream through. the hole '8, and, therefore, may he referred to for convenience as the shield.

While the dimensions of the mercury vapor device may be varied it is found that a mercury vapor device having substantially the followin dimensions operates successfully: The istance from the surface of the mercur to the shield 5 is about one-half inch. he distance from the shield 5 to the open work electrode or grid 8 is about five inches. The distance from the electrode 3 to the electrode 2 is about one and one-quarter inches. The shield 6 is about one inch in diameter and has a hole of about a quarter of an inch diameter throu h its center. The electrode or id 8 has su stantially a square outline of a cut one and one-ei hth inches across. The electrode 2 is a litt e less than an inch in diameter. .The pointed tip of the platinum wire 4, the hole the electrode or id 8 and the electrode 2 are all in line so t at the stream of electrons shot of! from the mercury are are directed through the center of the grid 8 against the middle of the electrode 2.

As far as the construction of the tube itself and the f keep alive circuit for the mercury are are concerned, the modifications illustrated in Figs. 1 and 2 of the drawings are identical.

In the apparatus illustrated in Fig. 1, 20 indicates a telephone line or circuit in which is included the primary 21 of a transformer 22, preferably a step-up transformer. One end of the secondary 2 of the transformer is connected b means of a'receptor lead 25 to the electro e 8 and the other end of the secondary is connected by means of a receptor lead 28 to the electrode 2. The leads 5 and 26 and their connections with the .elephone circuit constitute what may be termed the controlling circuit 28 by means of which the electrical potential variations set up in the transformer 22 are impressed upon the sensitive-ionized mercury va or inthe tube. The electrode 2 is connects with one of the are terminals, preferably the anode plate or shield is by means of the electric circuit 80 including a battery 81 and the primary 82 of the transformer 88. The cir ouit 80 since its current is varied or controlled by means of the mercury va or device may for convenience be re erre to as the controlled circuit. The negative pole of the battery 81 is connected to the electrode 2. The battery 81 has an electro-motive force of about one-half volt to live volts.

'cuit 30. This is probabl Thesecondary 34 bf the transformer 88 is connected to a telephone receiver 85 which constitutes the translating means by means of which the'signals are detected. Instead of the telephone receiver 35 the transformer may be connected .with a telephone line and the amplifiedtele honic waves relayed to a distant station. he batteryL 81 causes but a very small current flow t rough the cirdue to the fact that the directed stream 0 electrons shot off from the mercury arc and impin ng upon the electrodes 2 and 3 is what may e termed a convection current of negative electricity and thus acts in oplposition to the battery and pretty efiectua y prevents the battery from forcing any considerable current through the tube. When a telephone message is transmitted over the telephone line, corresponding variations in electro-motive force are impressed by means of the controlling circuit 28 u on the electrodes 2 and 3. These impresse variations cause corresponding changes or variations in the apparent conductivity of the sensitive gas in the tube and thereby cause corresponding variations to take place in the current in the circuit 3O. The current variations in the circuit 30 are usually of much greater energy than the variations in the telephone line 20. Thus the telephonic waves received over the telephone line 20 are amplified and may be heard in the receiver 85 or relayed to a distant station.

In Fig. 2 is illustrated an apparatus particularly adapted for use in connection with telegraph lines. The positive and negative wires 4-0 and 41 of the telegraph line are connected with the,electrodes 8 and 2 respectively, and constitute the controlling circuit 28 by means of which the variations of electro-motive force are im ressed u on the mercury vapor device. he contro led circult 80 is connected b tween the electrode 2 and the mercury arc and includes the battery 31, and the relay 42. The no ative pole of...

the battery 81 is connected to t e electrode 2. The battery has an'electro-motive force of from about one-halfvolt to five volts. The relay 42 operates upon an increase of current in the circuit 80 to close a local sounder 44. The relay 42 may, if dqsired, be used to control another telegraph lme by means of which the'relayed 'message may be transmltted to a distant station. When the teleraph key at the distant sending station is epresscd, the wire 40 and electrode 8 have,

a positive potential with relation to the wire 41 apd electrode 2, and this difference of potential force operates to increase the apparent conductivity-of the tube and so increase the current in the controlled circuit 30. When the sendin key is released at the end of the dot or das signal and thediflerence m potential of the wires 40 and 41 is no longer maintained, the tube restores itself to a condition of decreased conductivity and the current. in the circuit 30 is decreased. These variations in the controlled circuit 30 cause the relay 42 to operate and relay the dot and dash signals. The current increases in the controlled circuit 30 are usually variations of much greater energy than that of the signal impulses transmitted over the wires 40 and 41. Conse uently, the device may be employed to amp ify very faint received telegraphic messages.

The apparatus of the present invention is also applicable to wireless telegraphy and telephony. In use with wireless telegraphy or telephony, an arrangement similar to that illustrated in Fig. 1 is preferred, the principal difference being that the transformer 22 will be an oscillation transformer, and the transformer primary 21 will be con nected to the oscillation circuit of the wireless receiving system, as shown. for example, in my Lao-pending application Serial No. 803,357, filed of even date herewith. In this case. the train of Hcrtzian waves which make up the wireless signals cause correspondingly rapid oscillations in the relative potential of the electrodes 2 and 3. and this causes an increase in the current through the controlled circuit '10, as: long as the train of I-lertzian waves lasts. In the case of wireless telegraphy, the dots and dashes, each made up of a train or trains of Hertzian waves, will cause corresponding increases in the current in the controlled circuit 30 and the signals will he heard as dots and dashes in the telephone receiver 3:). in the case of wireless telephony. the telephonic wax es consist in variations of telephonic frequeue in the intensity of trains of waves of Hertzian frequency. \Yhcn a wireless telephone message is being received, the more intense the received train of waves is. the greater are the potential oscillations of llertzian frequency between the electrodes 2 and 3, and the greater is the battery current in the. cont rolled circuit 30. The variations of telephonic fre piency of intensity in the train of llertlzian waves. therefore, cause corresponding variations in the current flow in the circuit: 30, and consequently the telephonic waves are audible in the receiver 35'.

Vi'hilc the operation of the device is not perfectly understood, it is believed that there is a rectifying action at the open work electrode 3. and that a discharge of electricitv can take place in only one direction from the electrmle 3. The mercury vapor device per Se is described and claimed in in (.o-pcnding application Serial X0. 503,357. illt' l of even date herewith. One of the esential dilierenccs between the apparatus described in this application and that in my co-pending application is the arrangement of the battery 31 which, in the apparatus of an increased amount of current throughthe" tube 1 when the electrode 3 is made positive or oscillations are impressed upon it, where-"' as in the apparatus described in my co pending application Serial No. 803,357, the positive pole of the battery 31 is connected to the electrode 2 and operates to send a decreased amount of current through the tube 3, s

1 when the electrode 3 is given a negative charge or when oscillations are impressed upon it. In the drawings of my co-pending application Serial No. 803,357, are indicated a number of ways in which the amplifying apparatus of the present application might be connected with wireless systems, with this difference, however, namely, that whereas in the connections shown in said co-pending application a'condenser is interposed in one of the receptor leads 25 and 26 between the oscillation transformer and the mercury vapor tube, no such condenser would be used in the receptor leads and 26 between the oscillation transformer and the mercury vapor tube in applying the present apparatus to wireless work. The regionbetween the electrodes to which the controlling circuit is connected has impressed upon it static variatimis of electro-motive force and these static variations are apparently accompanied by more or less of a transfer of electricity between said electrodes. It will be noted that the region in the'tube subject to the action of the controlling circuit is not co-extensive with the region which forms the current path of the controlled circuit and that these regions have a. part only in common.

The expression controlling circuit, as used in the specification and claims is intended to define an electric circuit by means of which the electrical variations to be unrplified are impressed upon the sensitive conducting gaseous medium, and the expression controlled circuit is intended to define. the electric circuit which is controlled thereby.

The present invention is not limited to its illustrated embodiment, but maybe embodied in other constructions within the scope of the following claims.

I claim-- l. An apparatus for amplifying or delecting electrical variations having, in combination, an evacuated vessel, an ionizing means therein, two electrodes in the vessel 2. An apparatus for amplifying or detecting electrical variations having, in combination, an evacuated vessel, an ionizing means therein, an electrode in the vessel, a second electrode in the vessel between the ionizing means and the first electrode, a controlling electric circuit connected with the two electrodes, and a controlled electric circuit including a uni-directional stance of electro-motive force having its positive pole connected with the ionizing means and its negative pole connected with the first electrode.

3. An apparatus for amplifying or detecting electrical variations having, in combination, an evacuated vessel, ionizing means in the vessel, an electrode in the vessel, a sec- 0nd open work electrode between the ionizing means and the first electrode, a controlling circuit connected with the open Work electrode, and a controlled circuit including a uni-directional source of electro-motive force having a positive pole connected with the ionizing means and its negative Dole connected with the first electrode.

4. An apparatus for amplifying or detecting electrical variations having. in comhination, an evacuated vessel, an ionizing means for maintaining a body of sensitive conducting gas therein, means for impressing static electrical variations upon a region in the conducting gas. and a controlled circuit having through the conducting gas a current. path which has a part only in common with said region and including a imi-directional source of electro-mrnive force having its positive pole connected with the ionizing means and its negative pole connected with the electrode.

5. An apparatus for amplifying or detecting electrical variations having, in comhination, an evacuated vessel, ionizing means in the vessel, an electrode in the vessel, a controlled electric circuit including a uni-dime tional source of electro-motive force ha vingits positive pole connected with the ionizing means and its negative pole connected with the electrode, and means for increasing the apparent conductivity of the current path of the controlled circuit through the vessel comprising a second electrodeiandgacontrolvling circuit connected withthe first and second electrodes for impressingvariations o'f the electro-motive force upon said two electrodes.

6. An apparatus for amplifying or detecting electrical variations having, in com.- bination, an evacuated vessel, means ,for maintaining a mercury arc therein, two elec trodes, a controlling electric circuitconnected with the two electrodes, and a controlled circuit including a uni-directional source of electro-motive force having its positivevpole connected with the mercury arc and its ne ative pole connected with one of the electro es.

7. An apparatus for amplifying or detecting electrical variations having, in combination, an evacuated vessel, ionizing means in the vessel, an electrode exposed to the ionizing means, a controlled electric circuit including a unidirectional source of electromotive force tending to cause a current to flow between the electrode and ionizing ing static electrical variations upon a region in the conducting vapor, and a controlled circuit having through the conducting vapor a currentpath which has apart only in common with said region and including a unidirectional source of electromotive force having its positive pole connected with the ionizing means and its negative pole connected with the electrode.

GEORGE W. PIERCE.

lVitnesses:

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